In K2 Cloud, the Identity Sync Service is a microservice that serves the entire K2 Cloud platform, whether you have one or multiple SharePoint online instances. Identity data across all customer-specific K2 Cloud environments is consolidated into a single cache, regardless of how many SharePoint user providers are registered.  

The most common practice with K2 Cloud is a single SharePoint Online tenant with dedicated team sites for each K2 Cloud instance. For example, a team site for Production, a team site for Development, and so on. K2 Cloud cannot work with duplicate team site titles in a single SharePoint Online instance. 

In the case of multiple SharePoint instances (a separate instance for each K2 Cloud environment), it is important to have different site titles for SharePoint sites to prevent identity data from being overwritten. If you have a site title called “Finance” in two different SharePoint Online instances, both with User Providers being serviced by the K2 Identity Sync Service, the identity data from one instance/site will be overwritten by data from the other instance/site. So, our recommendation is to use unique site titles across your SharePoint instances.  

For example, "Finance-dev", "Finance-Test", and "Finance".

The SharePoint registration and activation wizard prevents you from registering sites with the same title by showing you an error message as follows: 

Instance '{instanceName}' already created with different site URL '{instanceFqn.Key}'.

Where '{instanceName}' would be the SharePoint site title and '{instanceFqn.Key}'  would be the SharePoint site URL.